The present invention relates to goggles for swimming or diving.
An extensive range of types of goggles for swimming is widely available commercially, the successors of the Polynesian or Japanese goggles from the start of the twentieth century, and these are characterized by a construction consisting essentially of two eyepieces that are completely separate. Each eyepiece consists essentially of a flat or curved lens, and a soft ring in which the lens fits hermetically, and rests with its annular rear edge on the immediate periphery of the eye and in some way or other inside the orbital cavity. The eyepieces are joined together by a flexible central bridge, which can also be adjustable. These goggles are provided with an elastic headband of adjustable length.
An example of goggles of this type is described and illustrated in U.S. Pat. No. 5,524,300.
Despite the fact that they are used very widely, swimming goggles of this type have two serious shortcomings, which cannot be eliminated as they are inherent in the design.
The first shortcoming consists of optical distortions due to refraction in water. This shortcoming arises from the fact that nothing is provided for the purpose of compelling the two lenses to take positions, if flat, on a single common plane and, if curved, following a single permanent surface of curvature that is predetermined by design. Once the goggles are being worn and the eyepieces are resting in the orbital cavities of the user, it is inevitable that the lenses will be positioned more or less at an angle, in the least unfortunate case with the respective normals lying in a single horizontal plane or, much more often, crooked on account of different angular positioning of the eyepieces in the orbits. In all cases there is doubling of vision into two images because the directions of virtual vision are different from the real directions, with the result that during use, the user is subject to a very troublesome sensation of nausea.
The second shortcoming consists of painful, non-hermetic orbital support of the two eyepieces. The fact that the two eyepieces rest on soft anatomical regions inside the orbital cavities makes the seal inefficient precisely because the respective rings do not have a solid contrast, unless the tension of the headband is exhausted. The effect is in any case painful, and certainly harmful to the health of the eye, in that it contributes to restriction of superficial blood circulation, and alteration of the values of ocular pressure. In the long term, from the medical standpoint this effect could become dangerous.
To avoid the two shortcomings described above, the applicant has proposed goggles of an entirely different type for swimming or diving, described in European patent application EP-A-0824029. These goggles contain a double (or theoretically also single) lens shaped according to a cylindrical surface with substantially rectilinear vertical generating lines with progressively variable radius of curvature, much greater corresponding to the front portion, and less corresponding to the lateral portions; a frame carrying the lens is shaped and arranged substantially according to the same cylindrical surface of the said lens; and a seal carried by the frame which can, during use, be applied with a tight seal on the user""s face, the arrangement being such that during use the lens is held very close to the surface of the user""s face.
In short, the characteristic features of the design of the goggles according to document EP-A-0824029 can be summarized as follows:
a lens that is substantially rigid (theoretically single but in practice formed from an assembly of two lenses held tightly together by a rigid supporting structure), with a curvature that has a quite precise geometry similar to a cylindroid with continuously variable radii and vertical generating lines, almost flat in the zone between the two optical axes and conversely with large radius of curvature in the two peripheral zones, with joints without an edge between the various zones of the lens, capable of providing an extremely panoramic visual field, free from discontinuities through the absence of dihedrals, without aberrations and refractive defects in the central zone, where the eye is perfectly capable of detecting optical imperfections, and in which the zones with strong refractive effect are relegated to the outermost right and left zones of the lens, where the eye is only capable of seeing indistinctly and so is not disturbed by refractive defects;
support on the face which, compared with an ordinary underwater mask, has a greatly reduced total area, and if compared with that of the traditional swimming goggles with binocular support is completely outside of the two orbital cavities, with the following advantages:
a) easy and secure sealing, since the support bears upon bony zones (forehead, cheekbones, nose) or on the compact facial muscles (cheeks);
b) no painful effect, and especially no adverse effect on the blood circulation and on ocular pressure even if considerable tension of the headband is required.
However, goggles of this type with rigid lens with predetermined cylindrical surface and very close to the surface of the user""s face, though completely solving the two aforementioned problems of the traditional binocular goggles, still have the following drawbacks.
Firstly, the advantages presented above are achieved by means of a relatively expensive construction, fully described and illustrated in the aforementioned European patent application EP-A-0824029, essentially comprising three components (pair of lenses+soft body that surrounds them and is supported on the face+plastics frame ensuring rigidity and hermeticity), assembled together by two lateral buckles for the headband. This construction requires expensive moulds, because jointed assembly of the various parts of the goggles requires the said moulds to have moving parts, and exceptional accuracy. Furthermore, sophisticated and controlled moulding techniques are required (abnormal shrinkage or fins can prevent connections within tolerance), and manual assembling is required, which cannot be automated and is therefore quite costly, because the soft body for surrounding the lens and for support on the user""s face cannot be manipulated by robots.
Secondly, although from the design standpoint the transparent element of the goggles really can be formed by a single lens, in practice the construction of the goggles makes this solution difficult to achieve except at high cost. In practical, commercial application of the goggles in question we are therefore essentially compelled to use a configuration with two lenses, each enveloped in its own annular rubber+plastics surround, though the result is inferior aesthetically to what would be desired on account of the presence, in the central zone between the two lenses, of a vertical bridge. Moreover, to guarantee the necessary rigidity of the assembly made up of the two lenses, the structure for connection and torsional-flexural stiffening between the two lenses is relatively heavy and, as already explained, expensive to manufacture.
The aim of the present invention is to make goggles of the type specified above which, while maintaining their advantages in terms of visual efficiency and user comfort, make it possible to eliminate the aforementioned shortcomings.
According to the invention, this aim is achieved essentially owing to the following combination of characteristics:
the frame is formed by a substantially flexible annular body made in one piece with the aforementioned surround by injection moulding of an elastomeric and preferably thermoplastic material,
the surround has an annular shape that describes a single continuous perimeter, substantially a horizontal figure-of-eight which is not closed at the centre, encircling both of the user""s eyes when in use, and
the lens consists of a substantially flexible sheet whose peripheral edge is formed with a large number of through-holes, and which is embedded hermetically in the said frame by being moulded simultaneously with the latter.
In other words, the goggles according to the invention are constituted of a single piece formed from a flexible lens; curved according to a progressive geometry described mathematically in the previously mentioned European patent application EP-A-0824029; embedded by simultaneous moulding in an integral soft body, formed by injection of elastomeric or thermoplastic material using a suitable mould, shaped so as to rest on the face describing a single continuous perimeter, on the anatomical sequence of left forehead-temple-cheekbone-cheek/root of the nose/right cheek-cheekbone-temple-forehead of the user.
With this solution, the functional effects that are typical of the goggles according to document EP-A-0824029 are maintained, but the following additional advantages are provided:
economical manufacture, both with regard to the capital cost of moulds and with regard to the technology of simultaneous moulding of lens and frame,
elimination of any stages of manual assembly,
support on the nose that is neither troublesome nor harmful, and with absolute hermeticity,
complete panoramic vision, also without discontinuities in the central zone of the lens.
Moreover, the flexibility of the assembly consisting of lens and frame, which is gradual and is without sharp changes in viewing angle that might cause discontinuities in underwater vision, permits simple adaptation to faces of different widths.
The lens can conveniently be single, but it can also be formed from two parts that are separate but rigid in flexure and torsion between themselves.